U.S. Pat. No. 3,227,554 discloses that in the development-processing of color photographic light-sensitive materials, pyrazolone couplers having an arylthio group at their respective coupling sites produce a sufficient color density as the magenta color image forming coupler. The couplers disclosed in the above patent are markedly inferior in light fastness of the magenta color image formed therefrom through photographic processing. On the other hand, magenta color images formed from pyrazolone couplers having an alkoxy group introduced at the position ortho to the phenylthio coupling eliminable group, which are disclosed in U.S. Pat. No. 4,351,897 and U.S. B-1 4,351,897, have a considerably improved fastness to light.
Increasing the processing speed in color development is a recent trend. For instance, processing solutions as described in WO-87/4534 are proposed for this purpose. However, pyrazolone couplers having a phenylthio group as a splitting group, and an alkoxy group at the ortho position, tend to produce a somewhat lowered color density when developed with the above-described processing solutions.
Under these circumstances, it has been strongly desired to design the magenta couplers with an arylthio group at the coupling active site so that the color images produced therefrom can have not only a sufficiently high fastness to light, but also a high maximum density even in rapid color development, particularly in color development having a processing time shortened to 2 minutes or less.